1. Field of the Invention
The present invention relates to a ratchet screwdriver in which a bit attaching section and a turning operation section are connected to each other through a ratchet mechanism so as to drive and loosen a screw by repeating operations for applying torque to the screwdriver in one direction.
2. Prior Art
Generally, a ratchet driver is very easy to handle, as compared with conventional screwdrivers comprising a bit fixed to a handle, since the ratchet screwdriver can be operated just by repeating operations for applying torque in one direction only.
There is, however, an increasing trend demanding a ratchet screwdriver capable of turning a screw with stronger torque and carrying out exact screwing and loosening operations under the background of diversified kinds of works.
In known ratchet screwdrivers, the turning operation section and the bit attaching section are coaxially coupled, and the turning operation section is formed into an integral one section. Accordingly, in such a conventional ratchet screwdriver, the turning operation section coaxially coupled with the bit attaching section needs to be operated directly and exclusively with its handle part. Thus, it is impossible to drive and loosen a screw strongly with high power since there is a limit in the torque produced by such a conventional ratchet screwdriver.
In order to meet the aforesaid increasing demand, a ratchet screwdriver was recently disclosed in Japanese Laid-Open Patent Publication (unexamined) No. 59-227369, and in this ratchet screwdriver, the turning operation section is divided into an operating section body serving as a connecting section with the bit attaching section and a handle section which is connected to the operating section body, and the handle section is rotatable in the direction where the axis of the handle section intersects that of the operating section body.
According to the disclosed ratchet screwdriver, a relatively strong torque can indeed be obtained by utilizing lever action. But a serious problem exists in that it is quite difficult to apply a force in the axial direction of the bit, since the handle section is in the direction perpendicular to the axial direction of the bit allowing only one-handed manual operation, eventually resulting in insufficient use of the increased torque. In other words, exact operation cannot be carried out by turning such a handle section.